That is exactly what you will need to do - get a syringe with a blunt tip needle and suck out the juice. With that said, you will likely not be able to get it totally in solution as there will be VG remnants and even a little causes separation. I was recently out of town and forgot new atomizers. My THC juice tank needed one so I used a tank that I normal nic juice in previously. The residual in the atomizer/on the sides of the tank made my perfect juice separate.
Go through the thread I posted if you want to learn how to make the juice. I would not recommend you putting straight oil into the tank. You need to mix it with PG/PEG first. Read the thread and it will make sense.
To remove the VG, you could always try to suck out what you can, winterize the oil, and then start over.
With all that said, I don't know why it didn't get you high. Even my separated juice worked. You just need to hit it to warm it up, shake it up a bit (the tank), and go.